The present invention relates to a pneumatic tire, more particularly to an improved axial groove structure which is capable of reducing uneven tread wear.
In pneumatic tires for heavy duty use such as truck/bus tires, in order to improve wet performance, snow performance and the like, block patters and block base tread patterns are widely used in recent years. In comparison with a rib, such a block is liable to wear unevenly at the heel edge and toe edge in particular (heel and toe wear). Hitherto, therefore, in order to prevent uneven wear, it has been usually employed to partially decrease the depths of tread grooves and/or to chamfer blocks"" corners. These measures however inevitably deteriorate the drainage performance, traction or road grip and the like.
It is therefore, an object of the present invention to provide a pneumatic tire, in which uneven wear can be effectively reduced without deteriorating the drainage performance, traction and the like.
According to the present invention, a pneumatic tire comprises a tread portion provided with at least one longitudinal main groove extending continuously in the tire circumferential direction and axial grooves each having at least one opening into the longitudinal main groove, and at least one of two groove walls of each of the axial grooves gradually swelling towards the at least one opening.